As part of the standard eye examination, replicated visual acuity assessments will be made during regularly-scheduled Clinic visits. Up to 500 opportunistically-sampled subjects from the National Eye Institute will be tested both with the ETDRS and EVA-MOBS protocols over a 12 month study period. Similar testing will take place at two other institutions (Devers Eye Institute, Portland, OR; The Retina Foundation of the Southwest, Dallas, TX) and the data from all three institutions will be combined and analyzed at the JAEB Center (Tampa, FL). Subjects will range in age from 7 years to 90 years and will be classified by clinical diagnosis (normal, high refractive error, age-related macular degeneration, cataract, optic nerve abnormality, corneal abnormality, uveitis, glaucoma, retinal/choroid abnormality, amblyopia and other criteria). First, those with poor acuity will be oversampled by increasing the chance that they will be selected for this testing. Second, patients will only be selected for this extra testing if it will not seriously delay clinic operations on any given day. Order of acuity test type will be randomized. It is estimated that up to 10 patients per day can have this testing performed without compromising clinic operations.